This report describes a family (in three consecutive generations) with the association of secundum atrial septal defect, conduction abnormalities on ECG and syncope. Electrophysiologic studies in selected members of this family showed evidence of atrioventricular nodal dysfunction. Hence, both atrial septal defect and A-V nodal disease may be transmitted as autosomal dominant traits and may occur together or separately in members of the same family.